Generally, a refrigerator works for 24 hours per day. The refrigerator accounts for one-third the total consumption of the electrical energy of the home appliance. The compressor uses about 80-90% of the power consumption of the refrigerator.
Therefore, much study with respect to the compressor has been conducted so as to enhance the efficiency thereof and reduce the power consumption.
However, so far since the compressor is fabricated in a method of using the crank shaft for converting the rotation movement of the motor into a linear reciprocating movement of the piston, the parts related to the crank shaft such as a connecting rod, a bearing, and the like are additionally necessary, so the number of elements are increased, and thus the fabricating cost is increased, thus degrading the productivity.
In addition, when the compressor is in operation, many friction occur between elements, so the efficiency of the compressor is degraded, and power consumption is increased.
Therefore, so as to resolve the above-mentioned problems, a linear compressor was introduced in the industry, which is directed to reciprocating the piston using a magnet and a coil without using the crank shaft.
Namely, the linear compressor is directed to reducing the fabricating cost and improving the productivity. In more detail, it is possible to increase the efficiency by more than 90% by reducing the friction portions between elements by reducing the number of elements, thus reducing the power consumption.
The linear compressor is directed to basically improving the efficiency by smoothly enabling the reciprocating movement of the piston.
In the industry, various types of the oil supply apparatus for a friction portion of the compressor was introduced, which was directed to smoothly enabling the reciprocating movement of the piston by supplying oil to the friction portion between the cylinder and the piston. Of which, for example, one conventional linear compressor equipped with the oil supply apparatus for a friction portion will now be described.
FIG. 1 shows the conventional linear compressor equipped with the oil supply apparatus for a friction portion. As shown therein, a cylinder 2 is disposed within a predetermined shaped hermetic housing 1.
Coil assemblies 3 and 3a are integrally engaged to the cylinder 2.
A piston spring 4 is provided at one side of the cylinder 2, and a piston 5 is connected to the intermediate portion of the piston spring 4 in order for the same to reciprocate within the cylinder 2.
A magnet 6 is disposed at the outer circumferential surface of the piston 5, and a plurality of mounting springs 7 for elastically supporting the piston spring 4 are elastically connected between the piston spring 4 and the hermetic housing 1.
Meanwhile, a valve assembly 8 is disposed at one side of the cylinder 2, and a suction-side muffler 9 and a discharging-side muffler 9a are mounted at both sides of the valve assembly 8.
An oil suction tube 10 is downwardly connected to a predetermined portion of the suction-side muffler 9 so as to suck the oil "O" filled in the bottom portion of the hermetic housing 1.
As shown in FIG. 2, the valve assembly 8 includes a suction gasket 11, a discharging gasket 15, a suction valve 12, a discharging valve 14, and a valve sheet 13. Here, the above-mentioned elements are tightly engaged to one another, and will be described in more detail.
First, a hole 11a is formed at the center portion of the suction gasket 11, and a predetermined shaped suction opening/closing portion 12a is movably attached at the center portion of the suction valve 12, and a discharging hole 12b is formed at one side of the suction opening/closing unit 12a.
In addition, a suction hole 13a is formed at the center portion of the valve sheet 13, and a discharging hole 13b is formed at one side of the suction hole 13a.
Meanwhile, a discharging opening/closing portion 14b is formed at a predetermined portion of the discharging valve 14 so as to open/close the discharging hole 13b of the valve sheet 13, and a suction hole 14a is formed at the center portion of the discharging valve 14.
In addition, a suction hole 15a is formed at the center portion of the discharging gasket 15.
In the drawings, reference numeral 16 denotes a head cover.
The operation of the conventional linear compressor will now be explained.
The conventional linear compressor includes the magnet 6 fixed to the coil assemblies 3 and 3a and the piston 5 which are fixed to the cylinder 2 for the major function of the linear motor.
In addition, so as to enhance the efficiency of the linear compressor, the piston 8 should most efficiently reciprocate in the system.
Therefore, when the piston 5 is moved in a predetermined direction indicated by the arrow "A" of FIG. 1 in the interior of the cylinder by an inertia energy and elastic energy which are generated by the coil assemblies 3 and 3a and the magnet 6, the pressure in a compressing space "C" is lowered, so that the refrigerant gas is introduced into the compressing space "C" of the cylinder 2 through the suction holes 15a and 14a of the discharging gasket 15 and the discharging valve 14.
Therefore, when the discharging opening/closing portion 14b of the discharging valve 14 closes the discharging hole 13b of the valve sheet 13, the refrigerant gas is introduced into the suction hole 13a of the valve sheet 13, so that the refrigerant gas pushes the suction opening/closing portion 12a in the right-side direction of FIG. 2, and then the refrigerant gas is introduced into the compressing space "C" of the cylinder 2 through the hole 11a of the suction gasket 11.
At this time, since the oil "O" filled at the bottom portion of the hermetic housing 1 is connected to the suction-side muffler, the oil "O" is sucked up along the oil suction tube 10 and then is introduced into the compressing space "C" together with the refrigerant gas along the flowing path of the refrigerant gas, and is supplied to the friction portion between the cylinder 2 and the piston 5.
Meanwhile, on the contrary, when the piston 5 is moved in the direction indicated by the arrow "B" of FIG. 1, the refrigerant gas is compressed in the compressing space "C", and the refrigerant gas pushes the suction opening/closing portion 12a of the suction valve 12 in the leftside direction of FIG. 2, and thus the suction hole 13a of the valve sheet 13 is closed.
Therefore, the refrigerant gas pushes the discharging opening/closing portion 14b of the discharging valve 14 through the discharging holes 12b and 13b of the suction valve 12 and the valve sheet 13, and then passes through the discharging gasket 15, and is discharged to the outside of the hermetic housing 1 through the head cover 16 and the discharging-side muffler 9a.
When the piston 5 continuously reciprocates within the cylinder 2, and the suction, compression, and discharging of the refrigerant gas is repeatedly performed, the oil "O" serves to enable a smooth reciprocating operation of the piston 5 in cooperation with the oil "O" provided at the friction portion between the cylinder 2 and the piston 5.
In more detail, when the piston 5 is moved in the direction indicated by the arrow "A" of FIG. 1, since the pressure in the compression space "C" is made lower, the oil "O" in the bottom portion of the hermetic housing 1 is sucked up along the oil suction tube 10 and then is introduced into the compression space "C" together with the suction refrigerant gas, and is supplied to the friction portion between the cylinder 2 and the piston 5.
However, since the conventional linear compressor has a disadvantage in that the oil "O" in the bottom portion of the hermetic housing 1 is supplied to the above-mentioned friction portion together with the suction refrigerant gas through the suction-side muffler 9. In addition, since the oil "O" introduced into the compression space "C" together with the suction refrigerant gas is not substantially provided to the cylinder 2 and the piston 5 and then is directly discharged through the discharging-side muffler 9a in cooperation with the compression operation of the piston, the oil "O" is not substantially supplied to the friction portion between the cylinder 2 and the piston 5.
In addition, since the conventional linear compressor has a disadvantage in that the oil is not substantially supplied to the friction portion between the cylinder and the piston, and a lot of the oil is directly discharged together with the compression refrigerant gas, whereby the cylinder heated due to the compression gas of the high temperature is not effectively cooled, thus reducing the efficiency of the compressor.